flywheels

[dsvracer]

customer just dropped off his lower end for a 117" conversion.  i put it on the truing stand to see where it was at. surprisingly it was pretty close at .002 on pinion side and .0025 on sprocket side.  my question is that when you roll it over it has the slightest tight spot. not on every revolution. when you spin it faster it doesn't seem to have any effect on the wheels. the motor has 49K miles on it and it never had any issues. should i be concerned >>  tia  dsv

[kd]

Who gets stuck for the engine rebuild if it fails later?  Will that 117 be beat on or did he want a 117 to just go for groceries? IMO there's 2 different criteria here.  It passes the runout test but is an early stage indication of a pending rod / crank pin failure.  I know what I would do.  At the very least share the information with the owner on the work order and let him enter the bottom end lottery himself.  Give him the option and responsibility.  It sounds like you already know what can happen or you wouldn't have posted the question. 

[Don D]

Pinched rods are common. I would press it apart and have a look at the bearings and pin condition also, assuming you do press together crank work at your shop or send it out.

[jsachs1]

I'd give the customer the option. I just did a 117" build 2 months ago with a little more run out than what I like to see. Gave the customer the option, and he agreed to replace the wheels. His decision.
John

[1workinman]

 

Who gets stuck for the engine rebuild if it fails later?  Will that 117 be beat on or did he want a 117 to just go for groceries? IMO there's 2 different criteria here.  It passes the runout test but is an early stage indication of a pending rod / crank pin failure.  I know what I would do.  At the very least share the information with the owner on the work order and let him enter the bottom end lottery himself.  Give him the option and responsibility.  It sounds like you already know what can happen or you wouldn't have posted the question. 

[dsvracer]

thanks guys.  i am informing the customer and let him decide what to do.  dsv

[koko3052]

Putting an engine together that is already showing signs of heart failure is not a very prudent move, JMO.

[dsvracer]

i agree with you , and now the customer does as well. dsv

[kd]

 

[838]

Good to see the pros collaborating to give the customers the best possible outcome. Nice work DSV!

[jmorton10]

I would not build a 117 with a stock lower end.  I have a 117 sitting on a shelf in my garage that scissored the stock flywheels & trashed the motor with only 1900 miles on it.

The motor was in the bike when I bought it from a buddy who needed the cash. He bought the bike new (2007 Roadking) & it was such a dog that he drove it straight to a well known builder & had the work done. It has axtell barrels & ported heads & ran GREAT when I got it.

I was just cruising around 50 mph headed to my house one day when it suddenly totally lost all oil pressure. When I started taking it apart the impellor in the oil pump fell out in 4 pieces. The pinion shaft runout was so severe I didn't need to use a dial indicator to measure it.  The shaft runout was so severe I could see it wobbling with no tools involved LOL.

I still have the bike, but now it is 124" with all S&S parts & runs great. I beat the sh** out of all my stroker motors running nitrous oxide & it hits the 6200 rpm rev limiter setting multiple times on every outing......I have stressed the new motor quite severely at times (long smokey burnouts/breaking the rear tire loose on 2>3 shifts with a Pingel air shifter etc.etc.) & the S&S parts are basically bullet proof.

~John

[dsvracer]

sorry to hear you had problems with your motor. I am sure you are aware of the fact that there are 1000's of 117/124's out there with 4.3/8 lower ends that are doing just fine. i do not think it is the size of the motor that gives the flywheels problems but more on how you drive it. better luck next time.  dsv

[jmorton10]

i do not think it is the size of the motor that gives the flywheels problems but more on how you drive it.

I completely agree, but I have been building & riding big stroker motors for years (I built a Panhead with 5" stroke flywheels in 1971).

I do not do any of the stupid things that cause lower ends to fail & until the flywheels scissored in that motor I had never had a lower end fail in that manner.

~John